The present invention relates to the regulation of gas flow within a conduit and, in particular, to the regulation of fuel gas flow within the fuel gas supply duct of a heating wall of a coke oven battery.
During the operation of a coke oven battery to produce coke for various purposes, a serious problem which arises is the loss of heat from the battery by radiation and especially from the ends of the battery. This problem is particularly manifested in the loss of heat from the ends of the ovens due to radiation from the outer surfaces of the end heating flues. As such, the end heating flues of the oven typically become cooler than the remaining oven heating flues. This problem is particularly attenuated when a coke oven battery is operated during a slowdown period or other period of reduced operation. During such reduced operations, the condition of lower temperature in the end flues of the heating wall is worsened due to the gas flow within the fuel gas supply duct being supplied under reduced pressure. This causes a lesser amount of fuel than is necessary to avoid a harmful temperature gradient to be provided to such end flues. Of most serious concern is the situation in which the coke oven battery is maintained in an "idle-hot" condition, that is, the oven is maintained heated but no coke is charged into the oven for production. During such idle-hot conditions, the fuel gas supplied by the fuel gas supply duct is much less than the oven was intended to accommodate and hence even less fuel gas is supplied to the end flues causing an even lower temperature in the end heating flues.
Various problems may arise due to the maintenance of an excessively low temperature in the end flues of a coke oven heating wall. For example, the temperature within the end heating flues may be insufficient to cause the intended ignition of the fuel gas. As such, fuel gas may collect in an area of lower temperature and then move into a higher temperature area causing the spontaneous ignition of an excessive amount of fuel gas resulting in a severe explosion within the heating flue with most disasterous consequences. Another problem which arises is damage to the refractory materials which form the heating flues of the oven due to the temperature thereof dropping below a critical point. The great expense necessary to correct such refractory damage must be immediately borne in order to avoid atmospheric pollution which may escape via cracks in the refractory and to maintain the structural integrity of the battery. A related problem is that due to the excessive temperature gradient between the end flues and the various other flues of the heating wall, the refractory materials may also become cracked or otherwise damaged also causing leakage of pollutants to the atmosphere and necessitating costly repair.
From the above, it is apparent that the likelihood of coke oven explosion and/or refractory damage during idle-hot operations is most significant. The current method of alleviating this problem in many coke ovens is to increase the flow of fuel gas to all heating flues to maintain the temperature in the end flues at a level sufficient to ignite all fuel gas and to prevent refractory damage due to contraction beyond a critical point. However, an excessive temperature gradient may still exist within the flues of each wall even when gas flow is increased.
Accordingly, it is an object of this invention to provide an apparatus and method for regulating the flow of fuel gas within the fuel gas supply duct of a coke oven to supply additional fuel gas to the end leaking flues in order to maintain a consistent temperature across the heating wall of a coke oven and avoid the unnecessary utilization of fuel gas.
It is another object of the present invention to provide an apparatus to regulate the flow of fuel gas within the fuel gas supply duct to provide for relatively balanced heating of the heating wall during slow-down operations of a coke oven battery.
While previous attempts have been made to alleviate the above-enumerated problems, no prior method or apparatus achieves all of the advantages of those of the present invention. One example of a prior attempt to deal with uneven coke oven heating during a slowdown in operations appears in U.S. Pat. No. 2,970,949 issued to Ernest Thompson, Jr. That patent teaches the use of a complicated fuel gas flow control insert. That device is intended to be positioned within the fuel gas supply duct of a coke oven heating wall and the design includes a bulky horizontal member of substantial length which includes an upward extending portion and a fixed, downward extending baffle. The Thompson apparatus requires that the horizontal member be supported by elongated parallel bars which must be affixed to a metallic liner within the fuel gas supply duct. That apparatus is intended to be positioned at various locations within the fuel gas supply duct to simply block fuel gas flow along the duct length to direct additional fuel gas into the end heating flues. In one embodiment of his invention, Thompson provides for a fuel gas control insert which includes a rotatable portion of the baffle in place of the completely fixed baffle. The problems with the Thompson design are first that it is not suitable for application in all types of coke ovens which employ a fuel gas supply duct or gun. For example, coke ovens of the Carl-Still design have only a small narrow aperture through the buckstays which communicates with the fuel gas supply duct. The fuel gas control means described by Thompson would certainly not be able to be inserted into such a coke oven design. In addition, the Thompson design provides a bulky, difficult to control means for regulating fuel gas supply which is only able to either redirect the fuel gas flow without allowing variation in flow rate or to only allow a minor variation in flow rate. Moreover, the complicated design of the '949 patent is most difficult to install and is costly and inefficient.
Another form of fuel gas supply regulator which has been employed in the fuel gas supply duct of a coke oven comprises a circular disc which is welded to the end of an extended rod for insertion into the fuel gas supply duct of, for example, a Koppers-Becker type coke oven battery. Such a design suffers from certain shortcomings similar to that of the Thompson apparatus. For example, since the flow control baffle in the latter-mentioned design is welded to the insertion rod, it is also not possible to pass such an apparatus through the narrow opening in the end of the fuel gas supply duct of a Carl-Still type battery. In addition, such a fuel gas control insert is not able to be manipulated within a fuel gas control duct so as to allow any variation in fuel gas flow. That is, the latter type of control means only provides a rigid baffle to redirect the fuel gas flow rather than that of the present invention which allows complete flexibility in flow control.
The subject invention is directed toward an improved means for regulating the flow of fuel gas within the fuel gas supply duct of a coke oven which overcomes, among others, the above-discussed problems and provides a control apparatus which is effective in the complete regulation of flow within the fuel gas supply duct of a coke oven while being of an uncomplicated, inexpensive, easy to install and useful design.